Elevator controller



June 1934- G. c. BROWN ELEVATOR CONTROLLER Filed March 1 20 1933 Patented June 5, 1934 UNITED STATES PATENT? OFFICE ELEVATOR CONTROLLER Glendon C. Brown, Milwaukee, Wis., assignor to Cutler-Hammer, Inc., Milwaukee, Wis., a corporation of Delaware This invention relates to control systems for an electric elevator and particularly to means for stopping and maintaining the car level with any of its several landings.

An object of the invention is to provide improved automatic leveling means effective when the elevator car is within a given distance from the landing at which it is to be stopped.

Another object is toprovide means of the aforementioned character which are highly sensitive and accurate and which, therefore, will bring and maintain the car much closer to the correct level than has heretofore been possible.

Another object is to provide means for the aforementioned purpose employing electron tubes which require a minimum amount of energy for their actuation.

Another object is to provide an electromagnetic balance which is influenced by the position of the car for the actuation and control of the elecand in addition thereto I mount on the elevator car an electromagnetic balance whose magnetic circuit may be closed by an armature mounted in the hatchway, in such a manner that the reluctance of the magnetic circuit is a minimum when the car is exactly level with a landing and that the reluctance of the two branches of the magnetic circuit is different when the car departs from the floor level. I use the voltage induced in a coil of said balance as a measure of the departure of the car from the desired level to afi'ect the reversing controller to affect leveling of the car.

The accompanying drawing illustrates the use of my invention in connection with a single speed elevator which is driven by a three phase squirrel cage motor. The invention, however, is applicable to other types of elevators such as multispeed elevators employing direct or alternating current.

In the drawing,

Figure 1 is a diagram of a controller embodying my invention.

Fig. 2 is a vector diagram of certain voltages of the controller in Fig. 1, and E Fig. 3 is a diagram of the relation of the voltige of an electron tube.

Referring to the drawing, L L and L are the terminals of a polyphase current supply system,

1 is a squirrel cage induction motor, having the terminals 1 1 and 1, the terminal 1 being directly connected to the line L while the terminals 1 and 1 may be reversibly connected to the lines L and L through electromagnetic switches 2 and 3, respectively. An electromagnetic brake B has its winding connected in parallel with motor terminals 1 and 1. The switch 2 has normally open main contacts 2 and 2 normally closed auxiliary contacts 2 and a magnet winding 2 while switch 3 has normally open main contacts 3 and 3 normally closed auxiliary contacts 3 and a magnet winding 3 The controller also includes two electromagnetic relays 4 and 5 having respectively magnet windings 4 and 5 and normally open contacts 4 and 5 Connected in series with the magnet windings 4 and 5, respectively, are gaseous electron discharge tubes 6 and '7, The tube 6 has a cathode 6 anode 6 and a control grid 6 while tube '7 has a cathode 7, anode 7 and control grid '1. The cathodes 6 and 7* may be heated in any well known manner, a battery b being shown for purposes of illustration. A control switch 8 having a contact lever 8 and stationary contacts 8 and 8 is provided for selective energization of the switches 2 and 3 for reversing the motor connections. The control switch has also a stationary contact 8 which is engaged when the switch is in the off position.

The motor drives an elevator cage 9. Mounted on the cage is an E-shaped transformer core 10 having on its outer legs windings 10 and 10 respectively, and on its central leg windings 10 and 10 Mounted in the hatchway and in line laterally with the transformer core 10 is an armature 11, one such armature being provided for each floor landing. When opposite the magnet core 10, the armature 11 reduces the reluctance of the magnet so as to increase the electromagnetic coupling between the coils 10 and 10 on the one hand and the central coils 10 and 10 on the other hand. The coils 10 and 10 are connected in series across the lines L and L They are wound in such a manner that the fluxes which they induce are in the same direction so as to normally produce no resultant flux passing through the central leg. On the other hand if the armature 11 is located near the structure 10 as indicated in dotted lines, it bridges the central and lower legs only and a flux will pass through the lower and central legs which induces a voltage in the coils 10 and 10 whereas if the armature should be nearer to the upper leg than to the lower leg, it induces in the coils 10 and 10 a voltage which is opposed to the voltage in the first case. The two coils 10 and 10 are wound in opposition relative to each other in such a manner that the voltage induced in one is the opposite to that induced in the other.

Connected across the lines L and L is a transformer 14 having a primary winding 14 and secondary windings 14 and 14. The secondary winding 14 is connected in a circuit from line L through winding 10, winding 14 through a resistance 12 to the grid 7, while winding 14 is connected in circuit from line I.- through winding 10, winding 14, resistance 13, grid 6.

Referring now to Fig. 2, E is the voltage impressed between the cathode and anode of the tube 6 or 7, E is the voltage induced in the corresponding secondary winding 14 or 14, respectively, while E is the voltage induced in the corresponding winding 10 or 10. The resultant E is the voltage impressed upon the grid of one or the other tube. It will be seen from Fig. 3 where the dotted line indicates the critical grid voltage, that as long as E is 180 out of phase with E, the tubes are non-conducting. If, however, a voltage E is induced in the coils 10 and 10, then the grid voltage is caused to lag more than 180 behind the plate voltage E, as shown by E and therefore permits the tubes to be:- come conducting during the first part of the positive half cycle. As these tubes are of the gaseous type they will then continue to conduct during the entire half cycle.

The equipment as a whole operates in the following manner: If the car is standing still and the operator wishes to move it in a downward direction, he throws the lever 8 to the left, thereby completing a circuit from line L .to contact 8 coil 2*, contact 3 to line L The'switch 2 is thus energized, thereby completing .the circuit to the motor and causing it to operate the car in a downward direction. As the car approaches the level at which the operator wishes to stop, he moves the lever 8 to the central position, thereby interrupting the circuit through the magnet winding 2 and de-energizing the switch 2 whereupon the motor is disconnected from the line, the brake B applied, and the car stops. However, if, at that moment, it is in such a position that the magnet core 10 has the position relative to the armature 11 indicated in dotted lines, a voltage E is induced in the winding 10 of such polarity that, at the beginning of the half cycle when the anode of the tube 6 is positive with respect to the cathode, the resultant grid voltage E is sufliciently positive to permit the tube to become conducting at the beginning of the positive half cycle. It thereby energizes the relay 4, the circuit extending from line L over contacts 8 and 3 winding 4, tube 6, to line L Relay 4 closes contacts 4' and thus establishes circuit connections for the magnet switch 2, shunting the break elfected by disengagement of contact arm 8 from contact 8 The mechanical and electrical inertia of relay 4 is suiiicient to prevent its vibration to break circuit during negative half cycles, when the tube 6 is non-conducting. The motor thus remains energized and the elevator moves down until the magnet core 10 is centrally located with respect to the armature 11. At this point no voltage is induced'in the winding 10 and therefore the grid potential E lags 180 behind the plate potentials. Under these conditions no current flow can be established during the positive half cycle through the tube 6 and the relay 4 is de-energized thereby de-energizing magnet switch 2 and disconnecting the motor from the line.

If the elevator should slide past the landing, the armature 11 will be so located with respect to the core 10 that the reluctance of the lower magnetic path is less than that of the upper path. Under these conditions, the voltage impressed upon the grid 6 at the beginning of the positive half cycle is negative but the voltage of the grid 7 during the beginning of the same half cycle is positive so that now the tube 7 becomes conducting thereby energizing the relay 5 which closes the circuit of the magnet coil 3, the energizing circuit of relay 5 extending from line L over contacts 8 and 8 winding 5, tube 7 to line L Magnet switch 3 thereupon responds and connects the motor terminals l and 1 to the lines L and L in the reverse direction from that previously described so that the motor is energized to lift the car until it is in the proper position relative to the armature 11, whereupon relay 5 and magnet switch 3 are again de-energized in the manner aforedescribed in connection with relay 4 and magnet switch 2. When the motor is energized, the winding of the electro-magnetic brake is also energized thereby lifting the brake on the motor shaft and permitting it to set again as soon as the motor and the brake circuits are interrupted.

If the operator desires to move the car in ,the upward direction, he moves the lever 8 to the right so as to make contact with the stationary contact 8 thereby energizing the coil 3 of the switch 3 and causing the elevator to operate in the reverse direction from that first described. The automatic leveling arrangement in this case operates as already described.

What I claim as new and desire to secure by Letters Patent is:

1. The combination with an elevator car, a motor for driving said car, electromagnetic reversing means, and switch means for controlling the operation of said car between landings, of leveling means connected in circuit when said switch means are in the off position and the car is near a landing, including a transformer having relatively movable parts, one part mounted on the car and another part located at a landing and adjacent to the path of said first part, said transformer being provided with primary and secondary windings so arranged that a voltage is induced by the former in the latter which varies in accordance with the position of the car relative to a landing, a supply of fixed voltage and means to impress a resultant voltage of said fixed and said varying voltage upon said leveling means to control said motor to effect leveling of said car.

2. The combination with an elevator car, a motor for driving said car, electromagnetic reversing means, and switch means for controlling the operation of said car between landings, of leveling means to control said electromagnetic reversing means connected in circuit when said switch means are in the off position and the car is near a landing, including electronic means, a transformer having relatively movable parts,

one part mounted on the car and another part located at a landing and adjacent to the path of said first part, said transformer being provided with primary and secondary windings so arranged that a voltage is induced by the former in the latter which varies in accordance with the position of the car relative to the landing, a supply of fixed voltage, and means to impress a resultant voltage of said fixed and said varying voltage upon said electronic means to control said motor to effect leveling of said car.

3. The combination with an elevator car, a motor for driving said car, an alternating current source, electromagnetic reversing means, and switch means for controlling the operation of the car between landings, of leveling means connected in circuit with said reversing means when said switch means are in the oflf position and the car is near a landing, including electronic means, a transformer having relatively movable parts, one part mounted on the car and another part located at a landing and adjacent to the path of said first part, said transformer being provided with a primary winding connected to said source and a secondary winding arranged to have induced therein a voltage varying in accordance with the position of the car relative to the landing, and means to impress a resultant of the voltage of said source and said varying voltage upon said electronic means to control said motor-to effect leveling of said car.

4. The combination with an elevator car, a motor for driving said car, an alternating current source, electromagnetic reversing means, and switch means for controlling the operation of the car between landings, of leveling means connected in circuit with said reversing means when said switch means are in the off position and the car is near a landing, including a gaseous electron discharge tube having a grid, a transformer having relatively movable parts, one part mounted on the car and another part located at a landing and adjacent to the path of the first part, said transformer having a primary winding connected to said source and a secondary winding arranged to have induced therein a voltage which varies in accordance with the position of the car relative to the landing, and means to impress a resultant of the voltage of said source and said varying voltage upon the grid of said tube to control said motor to effect leveling of said car.

5. The combination with an elevator car, a motor for driving said car, an alternating current source, electromagnetic reversing means, and switch means for controlling the operation of said car between landings, of leveling means connected in circuit with said reversing means when said switch means are in the off position and the car is near a landing, including two gaseous electron discharge tubes, one for each direction of operation of said car, each of said tubes having a grid, a transformer having relatively movable parts, one part mounted on the car and the other part located at a landing and adjacent to the first part, said transformer having a primary winding connected to said source and a secondary winding arranged to have induced therein a voltage whose magnitude and phase varies in accordance with the position of the car relative to a landing and means to impress the resultant of the voltage of the source and of said varying voltage upon said grids to thereby control said motor to effect leveling of said car.

GLENDON C. BROWN. 

